The present invention relates to Mobile IP network technology. More specifically, this invention relates to mechanisms for generating a Mobile-Home authentication key to be used to support mobility of a Mobile Node during a single Mobile IP session.
Mobile IP is a protocol which allows laptop computers or other mobile computer units (referred to as “Mobile Nodes” herein) to roam between various sub-networks at various locations—while maintaining internet and/or WAN connectivity. Without Mobile IP or a related protocol, a Mobile Node would be unable to stay connected while roaming through various sub-networks. This is because the IP address required for any node to communicate over the internet is location specific. Each IP address has a field that specifies the particular sub-network on which the node resides. If a user desires to take a computer which is normally attached to one node and roam with it so that it passes through different sub-networks, it cannot use its home base IP address. As a result, a business person traveling across the country cannot merely roam with his or her computer across geographically disparate network segments or wireless nodes while remaining connected over the internet. This is not an acceptable state-of-affairs in the age of portable computational devices.
To address this problem, the Mobile IP protocol has been developed and implemented. An implementation of Mobile IP is described in RFC 3344 of the Network Working Group, C. Perkins, Ed., “IP Mobility Support for IPv4,” August 2002. Mobile IP is also described in the text “Mobile IP Unplugged” by J. Solomon, Prentice Hall. Both of these references are incorporated herein by reference in their entireties and for all purposes.
The Mobile IP process in a Mobile IPv4 environment are illustrated in FIG. 1. As shown there, a Mobile IP environment 2 includes the internet (or a WAN) 4 over which a Mobile Node 6 can communicate remotely via mediation by a Home Agent 8 and may also include a Foreign Agent 10. In the absence of a Foreign Agent in a Mobile IPv4 environment, or in a Mobile IPv6 environment in which a Foreign Agent is not implemented, the Mobile Node 6 can obtain a topologically correct IP address (i.e., collocated IP address) and register this IP address with the Home Agent. (In a Mobile IPv6 environment, this is accomplished via an Access Router rather than a Foreign Agent.) Typically, the Home Agent and Foreign Agent are routers or other network connection devices performing appropriate Mobile IP functions as implemented by software, hardware, and/or firmware. A particular Mobile Node (e.g., a laptop computer) plugged into its home network segment connects with the internet through its designated Home Agent. When the Mobile Node roams, it communicates via the internet through an available Foreign Agent. Presumably, there are many Foreign Agents available at geographically disparate locations to allow wide spread internet connection via the Mobile IP protocol. Note that it is also possible for the Mobile Node to register directly with its Home Agent.
As shown in FIG. 1, Mobile Node 6 normally resides on (or is “based at”) a network segment 12 which allows its network entities to communicate over the internet 4 through Home Agent 8 (an appropriately configured router denoted R2). Note that Home Agent 8 need not directly connect to the internet. For example, as shown in FIG. 1, it may be connected through another router (a router R1 in this case). Router R1 may, in turn, connect one or more other routers (e.g., a router R3) with the internet.
Now, suppose that Mobile Node 6 is removed from its home base network segment 12 and roams to a remote network segment 14. Network segment 14 may include various other nodes such as a PC 16. The nodes on network segment 14 communicate with the internet through a router which doubles as Foreign Agent 10. Mobile Node 6 may identify Foreign Agent 10 through various solicitations and advertisements which form part of the Mobile IP protocol. When Mobile Node 6 engages with network segment 14, Foreign Agent 10 relays a registration request to Home Agent 8 (as indicated by the dotted line “Registration”). The Home and Foreign Agents may then negotiate the conditions of the Mobile Node's attachment to Foreign Agent 10. For example, the attachment may be limited to a period of time, such as two hours. When the negotiation is successfully completed, Home Agent 8 updates an internal “mobility binding table” which specifies the care-of address (e.g., a collocated care-of address or the Foreign Agent's IP address) in association with the identity of Mobile Node 6. Further, the Foreign Agent 10 updates an internal “visitor table” which specifies the Mobile Node address, Home Agent address, etc. In effect, the Mobile Node's home base IP address (associated with segment 12) has been shifted to the Foreign Agent's IP address (associated with segment 14).
Now, suppose that Mobile Node 6 wishes to send a message to a Correspondent Node 18 from its new location. In Mobile IPv4, a message from the Mobile Node is then packetized and forwarded through Foreign Agent 10 over the internet 4 and to Correspondent Node 18 (as indicated by the dotted line “packet from MN”) according to a standard internet protocol. If Correspondent Node 18 wishes to send a message to Mobile Node—whether in reply to a message from the Mobile Node or for any other reason—it addresses that message to the IP address of Mobile Node 6 on sub-network 12. The packets of that message are then forwarded over the internet 4 and to router R1 and ultimately to Home Agent 8 as indicated by the dotted line (“packet to MN(1)”). From its mobility binding table, Home Agent 8 recognizes that Mobile Node 6 is no longer attached to network segment 12. It then encapsulates the packets from Correspondent Node 18 (which are addressed to Mobile Node 6 on network segment 12) according to a Mobile IP protocol and forwards these encapsulated packets to a “care of” address for Mobile Node 6 as shown by the dotted line (“packet to MN(2)”). The care-of address may be, for example, the IP address of Foreign Agent 10. Foreign Agent 10 then strips the encapsulation and forwards the message to Mobile Node 6 on sub-network 14. The packet forwarding mechanism implemented by the Home and Foreign Agents is often referred to as “tunneling.” In the absence of a Foreign Agent, packets are tunneled directly to the Mobile Node 6 collocated care-of address.
The Mobile IP protocol typically requires the configuration of security associations between three entities: the Mobile Node, the Home Agent, and the Foreign Agent. The security-association defines an authentication key and an algorithm to be applied during the authentication process. Specifically, the authentication keys that typically need to be configured are the Mobile-Home authentication key on the Mobile Node and the Home Agent, the Foreign-Home authentication key on the Foreign Agent and the Home Agent (in a Mobile IPv4 environment), and the Mobile-Foreign authentication key on the Mobile Node and the Foreign Agent (in a Mobile IPv4 environment). These keys are typically statically configured on the Home Agent, Foreign Agent, and Mobile Node.
In enterprise deployments, configuration of the authentication keys among the large number of entities is a challenging, complex and tedious administrative task. Patent application Ser. No. 10/635,882, entitled “METHODS AND APPARATUS FOR DYNAMIC SESSION KEY GENERATION AND REKEYING,” by Patel et al and patent application Ser. No. 10/328,522, entitled “METHODS AND APPARATUS FOR AUTHENTICATING MOBILITY ENTITIES USING KERBEROS,” by Leung et al each discloses a mechanism for dynamically generating a Mobile-Home authentication key on both the Home Agent and the Mobile Node, and are incorporated herein by reference for all purposes.
Typically, the dynamic generation of keys such as Mobile-Home authentication key requires some sort of mutual authentication between the Mobile Node and the network. Specifically, the identity of the Mobile Node is generally authenticated in the Mobile IP environment in order to ensure that the dynamic generation of the Mobile-Home authentication key is a secure process.
In many networks today, there are other mechanisms that perform authentication of the Mobile Node, such as those performed at the Data Link Layer (Layer 2) or the Network Layer (Layer 3). For instance, authentication at the Point-to-Point Protocol (PPP) layer or the Extensible Authentication Protocol (EAP) layer may be performed. As a result, the authentication process typically performed in the Mobile IP environment is often a duplicative process. In such environments, since the basic network access is authenticated and secure, having yet another level of authentication merely increases barriers to deployment.
Similarly, “open networks” support roaming, but security credentials are not provisioned. In these networks, security is implied from physical presence in the network. As a result, authentication at the user level is not required. In an “open network,” authentication within the Mobile IP environment is similarly unnecessary.
In view of the above, it would be beneficial if a simplified mechanism for dynamically generating Mobile-Home authentication keys could be established.